It is now well established that angiogenesis is an important contributor to the pathogenesis of a variety of disorders. These include solid tumors and metastasis, intraocular neovascular diseases such as retinopathies, e.g., diabetic retinopathy, retinal vein occlusion (RVO), wet age-related macular degeneration (AMD), neovascular glaucoma, immune rejection of transplanted corneal tissue and other tissues, and rheumatoid arthritis. Duda et al. J. Clin. Oncology 25(26): 4033-42 (2007); Kesisis et al. Curr. Pharm. Des. 13: 2795-809 (2007); Zhang & Ma Prog. Ret. & Eye Res. 26: 1-37 (2007).
The retina receives its blood supply from retinal vessels, which supply the inner part of the retina, and choroidal vessels, which supply the outer part. Damage to retinal vessels occurs in several disease processes including diabetic retinopathy, retinopathy of prematurity, and central and branched retinal vein occlusions (ischemic retinopathies). Retinal ischemia from this damage results in undesirable neovascularization. Choroidal neovascularization occurs in a number of other disease processes, including AMD. In contrast, incomplete vascularization of the retina is a hallmark in patients with certain genetic diseases, e.g. familial exudative vitreoretinopathy (FEVR), Coats' disease, and Norrie disease caused by mutation of the Wnt receptor Frizzled4 (Fzd4), the co-receptor LRP5 or the secreted ligand Norrin (Berger et al. Nature Genet. 1:199-203 (1992); Chen et al. Nature Genet. 1:204-208 (1992); Robitaille et al. Nature Genet. 32:326-30 (2002); Toomes et al. Am. J. Hum. Genet. 74:721-30 (2004)). An additional protein, TSPAN12, has been shown to be involved in Norrin signaling (Junge et al. Cell 139:299-311 (2009) and WO 2010/030813). Mutations in the Tspan12 gene are also reported to be causal for FEVR (Poulter et al. Invest Ophthalmol V is Sci. 14; 53(6):2873-9 (2012); Yang et al. Molecular Vision 17:1128-1135 (2011); Poulter et al. The American Journal of Human Genetics 86, 248-253 (2010)). Models for these genetic diseases are available in mice knocked out for the corresponding homologous genes.
Despite the many advances in the field of ocular angiogenesis, there remains a need to identify targets and develop means that can supplement or enhance the efficacy of existing therapies.